Seed Production of Native Catfish
The freshwater catfish Clarias macrocephalus is native to the Philippines but is fast becoming scarce in many natural habitats. It is a favorite food fish due to its tender and delicious meat. Recently, farming of C. macrocephalus has gained interest among catfish growers. Like other catfish species, it is resistant to diseases, can be stocked at high densities, and tolerates low water quality. The catfishes C. macrocephalus and C. batrachus are almost similar in size and appearance, but differ by the shape of the occipital process in the head portion. The occipital process is blunt or rounded in C. macrocephalus and pointed in C. batrachus. C. macrocephalus also has small white spots along the sides of the body.
Broodstock development and management
Catfish broodstock can be obtained from lakes, rivers, tributaries and other freshwater bodies, and caught by hand or indigenous fish traps. C. macrocephalus was reported to abound in the Bicol region, Palawan, and some areas in Mindanao. Sexes are separate in catfish. Males have elongated urogenital papillae around the anus, whereas females have a simple round opening.
Catfish are carnivores, but can feed on small bottomdwelling animals, rice bran, kitchen refuse, fish meal, or formulated feeds. Broodstock fed a SEAFDEC-formulated diet with 43% protein had similar reproductive and larval quality as those fed ‘trash fish.’ Catfish mature at about 6-8 months of age. Larger mature females produce more eggs than smaller females. About 20-90 eggs/g body weight (BW) can be stripped from a gravid female after hormone injection.
Captive C. macrocephalus contain eggs and sperm the whole year but do not spawn by themselves. Artificial propagation of C. macrocephalus involves inducing the gravid females to spawn by injection
of different hormones, and manually stripping the eggs after several hours. Before females are stripped of eggs, male catfish are sacrificed. The male reproductive tract is then dissected and macerated to obtain the milt to fertilize the eggs. Success in induced spawning depends largely on knowledge of (i) the optimum dose of hormones to be used, and (ii) latency period, the time between injection of hormones and stripping of eggs. Induced spawning of C. macrocephalus can be done in any of the following ways:
Four to five days after hatching, catfish larvae are stocked at 30 per liter in bigger tanks. They are fed natural food organisms such as newly hatched brine shrimp Artemia for three days, and the water flea Moina for another four days. Thereafter, larvae can be weaned to formulated diets with 44% protein and particle size 150-200 µm. The diet is given twice daily to two- to four-week old catfish fry at a feeding rate of 20% BW and to older fry at 5-10% BW.
The nursery tank or pond is fertilized ten days before stocking of catfish fry. Fifteenday old fry may be stocked at 200-800/m2 in tanks and up to 1200/m2 in ponds. More fingerlings can be obtained when the fry are grown in net cages suspended in either tanks or ponds. Fingerlings are harvested after 28 days, ready for stocking in grow-out ponds.
For more information, contact:
SEAFDEC Aquaculture Department
Tigbauan, Iloilo, Philippines
Tel: 63 (33) 335 1009, 336 2965,
Fax: 63 (33) 3351008, 336 2891
Email: [email protected]